Continuous flow wafer impregnator and digest tube



Dec. 27, 1966 w. R. MATTHEWS CQNTINUOUS FLOW WAFER IMPREGNATOR AND DIGEST TUBE 2 Sheets-Sheet 1 Filed July 15, 1963 I I I r I I r! w M 5 OF- I mm OO O O O o 0 0 0 O o R O 00000 O O O O 0 O O oo o M oo o oo A 0000 000 MI I O O OO O U 0 O O I O 000 a 00000 W o oo o um 0 oo o O O 00 000000 0 1/ o o 00 0 000 m 1 1 F]. \N T N ATTvs.

Dec. 27, 1966 w. R. MATTHEWS CONTINUOUS FLOW WAFER IMPREGNATOR AND DIGEST TUBE 2 Sheets-Sheet 2 Filed July 15, 1963 INVENTOR WILLIAM R. MATTHEWS ATTYs.

United States Patent Ofiice Patented Dec. 27, 1966 3,294,626 CONTINUOUS FLOW WAFER IMPREGNATOR AND DIGEST TUBE William R. Matthews, W. 1022 7th Ave., Spokane, Wash. 99202 Filed July 15, 1963, Ser. No. 295,025 7 Claims. (Cl. 162--236) My invention is directed to an improvement in the means for moving wood wafers and chips continuously through a tube and impregnating them with a pulping liquid or the like.

In continuous digesting systems one of the problems involved in continuous digesting is that the wafers, if they are of the preferred type for good digesting, will be inclined to stick together with the fiat sides facing each other. This makes it difiicult to get uniform impregnation of the chips when they are first contacted with the liquid. The cohesion between the wafers makes a double thickness or more, and this prevents complete penetration of the pulping liquor in the time that it takes the chips to move through the tube.

It is the purpose of this invention to provide a digester tube having a screw feed for advancing the wafers with means to improve the separation of the wafers and thus provide greater assurance that all of the chips will be subjected to the pulping liquor long enough for impregnation for the desired digestion.

It is also a purpose of the invention to provide an improved circulation system within the continuous digester tube whereby the flow of the liquor is cross current with respect to the wafers or chips.

It is a further purpose of the invention to provide a digester or impregnator tube with a novel heating area which avoids the necessity of injecting gas or steam into the moving mass of wood and which aids physically in removing any gases or vapors from the mass of wood While it is travelling.

The nature and advantages of this invention will appear more fully from the following description and the accompanying drawings wherein a preferred form of the invention is shown. It should be understood, however, that the drawings and description are illustrative only and are not intended to limit the invention in scope except insofar as it is limited by the claims.

In the drawings:

FIGURE 1 is a somewhat diagrammatic single line drawing of an impregnator and digester tube;

FIGURE 2 is an enlarged sectional view taken on the line 22 of FIGURE 1;

FIGURE 3 is a sectional view taken on the line 3-3 of FIGURE 2;

FIGURE 4 is an enlarged sectional view taken substantially on the line 44 of FIGURE 1 and FIGURE 5 is a sectional view taken on the line 55 of FIGURE 4.

Referring now to the drawings, my invention is embodied in an impregnator digester tube which has an inlet opening at 11 for receiving wood particles such as wafers or chips. At the other end of the tube 10 it is provided with an outlet 12 for discharge of the wood particles.v Transfer of the particles through the tube 10 is by means of screw conveyor units 13, 14, 15 and 16, all of which are secured upon a shaft 17 which is driven at a relatively slow rate by any suitable means. A drive pulley 18 is shown on shaft 17 at the input end of the tube 10. The digester tube is provided with a liquor inlet at 19 and a liquor outlet at 20. It is also provided with a gas and vapor outlet at 21. The discharge end of the tube 10 is closed by a member 22 which may be transparent to permit visual inspection of a screw 23 which is placed between the wood particle outlet 12 and the liquor drain outlet 20.

This screen carries bearing 24 for the support of the shaft 17 at the discharge end of the tube. The shaft 17 carries a doctor blade 25 that operates against the screen 23 to wipe off any wafers or wood particles that tend to block the screen opening.

The detailed construction of the tube 10 is shown best in FIGURES 2, 3, 4 and 5. It Will be noted that the tube is of a composite construction. The screw conveyors are surrounded entirely by an inner sleeve 26. This cylindrical sleeve 26 extends the full length of the unit. It has a lower perforated section 20a and an upper perforated section 26b that are diametrically opposite each other. These sections are covered by substantially semicircular troughs 27 and 28. The unperforated portions of the sleeve 26 have electric heating units 29 and 30 covering them. These heating units may be of any suitable type such as the well known Calrod heaters. Heat insulation 31 surrounds the entire assembly and is particularly heavy on the exterior of the heating units 29 and 30. To complete the assembly a protective shield 32 is provided. This shield 32 is sectionalized as indicated in FIGURES 2 and 4 at 33.

The liquor entering at 19 passes along the chamber provided by the trough 27 and flows up through the perforated portion 26a and forces any air or gas upwardly through the perforated portion 26b. This gas is free to travel along the inverted channel 28 to the outlet 21 and thus escape. Whenever it is desired to operate under pressure then increased circulation can be had with both gas and liquor escaping at 21 and the gas can be removed at some exterior point in the circulation system.

The WOOd particles traveling lengthwise of the tube 10 under the influence of the screw conveyors 13, 14, 15 and 16 is subjected to a cross current of the liquor which rises through the perforated portion 26a. This provides a lifting action on the particles and helps to separate them and prevents layering. However, when the particles are substantially flat wafers they need additional means to effect separation and prevent them from remaining in overlapped plated relation as they travel through the machine. In order to break up the layers and agitate the particles, 1 provide a plurality of agitator wheels 34, 35 and 36 at spaced intervals lengthwise of the tube 10. These agitator wheels have their hubs rotatably mounted on the shaft 17 as illustrated in FIGURE 5, where the hub 34a of the agitator 34 is shown as secured between two collars 37 and 38 on the shaft 17 so that it may rotate. The collars serve as end bearings for the hub 34a. The agitator wheels 34, 35 and 36 carry ring gears 39 which mesh with pinions 40 on a shaft 41 that extends from the discharge end of the tube 10 along the inverted channel 28. By driving the shaft 41 the agitator wheels are turned at a relatively rapid rate with respect to the general movement of the material by the screws 13, '14, 15 and 16 so that the blades such as 34b of the agitator wheels will agitate the wood particle and further break up any layering that occurs. Since all of the particles must pass through the blades of the agitator wheels and thus tumble and rotate this gives a positive means of break up of any cohesion between particles and getting out any gas that is trapped in the particles.

The upper perforated portion 26b of the sleeve 26 is cut out as indicated at 42 in FIGURE 4, to permit meshing of the pinion 40 with the ring gear 39. The lubricant for the gears and for the bearing of the hub 34a on the shaft 17 is the liquor itself. It is desirable also to provide means to prevent packing of wood particles in the teeth of the pinion and gear. To accomplish this I provide jet tubes 43 that extend through the inverted channel 28 and that are directed to the areas of the pinion and gear where they mesh. I inject pulping liquor at high pressure through these jet members 43 to wash out any particles from the teeth.

The shafts 17 and 41 are, of course, sealed where they enter the tube so that the device may be operated under pressure. One such shield is shown at 44 in FIGURE 3 and the other is shown at 45 in FIGURE 1. These shields are, of course, well known and the details'thereof are not shown.

It is believed that the operation of this device will be clear from the foregoing description. The invention is particularly useful in connection with the impregnation of dry wood particles as described in my co-pending application, Ser. No. 295,017 wherein the particles are essentially dried to remove imbibed water but leaving the actual cell moisture therein and then while heated, the particles are subjected to impregnation with a hydrotropic salt solution which is at a lower temperature than the particles. For example, it is contemplated that the dry wood particles will enter the inlet '11 at a temperature of approximately 110 degrees C. The hydrotropic salt solution is, however, at a temperature below 100 degrees C. since it is not desirable to have it above the boiling temperature of water. Preferably I may bring the hydrotropic solution to a temperature of 72 degrees C. to 80 degrees C. and then use the heating elements 29 and 30 to maintain the temperature within the tube 10 at about 90 degrees C. to 95 degrees C. I have found this to be effective in the impregnation 01f the dry particles so that the hydrotropic salt solution which is particularly useful in dissolving the lignin from the wood particles, will be fully taken up by the particles and thoroughly impregnate them. By having the wood particles hotter than the liquid solution I find that I am able to more effectively remove the gases that may be left in the wood as it comes from the drier and this is important, for the gases, if they are not removed, do block the adsorption of the liquor into the spaces between cells where the heaviest lignin concentration is found.

The construction I have just described may be used either as an impregnator of dry wood particles, or as a digester of particles that have already been impregnated. In the latter case the electric heating elements may be used to bring the temperature to any desired level without the necessity of using steam with its dilution effects upon the pulping liquor. This is particularly important with hydrotropic salt solution pulping wherein the efiectiveness of the solution as a solvent for lignin is destroyed by dilution below a certain level. The cross current circulation may, of course, be speeded up to any desired level, depending upon the amount of liquid that is pumped between the inlets and outlets. In use of the tube for sulfite digesting this is effective in getting the gases out of the pulping as rapidly as possible.

Having described my invention, I claim:

1. A device for liquid impregnation and treatment of cellulosic materials comprising an elongated cylindrical sleeve having an inlet at One end thereof and an outlet adjacent the other end thereof;

screw feed means in said sleeve for advancing the material from the inlet to the outlet;

a fluid supply conduit on the exterior of the sleeve extending lengthwise of the sleeve;

the sleeve having a band of apertures in its wall leading into said conduit;

5 a fluid discharge conduit on the exterior of the sleeve diametrically opposite to the supply conduit and extending lengthwise of the sleeve;

the sleeve having a band of apertures in its wall leading into said discharge conduit whereby fluid forced into said sleeve from the supply conduit may flow across the sleeve to the discharge conduit.

2. A device for liquid impregnation and treatment of cellulosic materials comprising an elongated cylindrical sleeve having an inlet at one end thereof and an outlet adjacent the other end thereof;

screw feed means in said sleeve for advancing the material from the inlet to the outlet;

a fluid supply conduit operable to supply fluid to the interior of the sleeve;

said screw feed means comprising a plurality of spaced apart screw sections fixed on a shaft that extends through the sleeve and has means thereon by which it may be rotated;

agitation wheels journalled on the shaft between the screw sections; and

means to rotate said wheels on the shaft.

3. The device defined in claim 1 wherein the sleeve has a recticulated partition means at the end thereof beyond the outlet for escape of fluid; and

wiper means engaging the inner [face of the partition means to wipe the cell'ulosic material therefrom.

4. The device defined in claim 1 wherein the supply and discharge conduits comprise troughs having open sides toward said apertures, the edges of said troughs being sealed to the sleeve.

5. The device defined in claim 1 wherein heating elements are provided on the exterior of said sleeve overlying the imperforate walls thereof between the bands of apertures.

6. The device defined in claim 2 wherein the means to rotate said Wheels comprises a shaft in one of said conduits having pinions thereon; and

the wheels having gear teeth thereon meshing with said pinions through the apertured Wall of the sleeve.

7. The device defined in claim 2 wherein the means to rotate said wheels comprises a shaft in one of said conduits having pinions thereon;

the wheels having gear teeth thereon meshing with the pinions through the apertured wall of the sleeve; and jet tubes are directed through the conduit toward the the areas Where the pinions and gear teeth mesh.

References Cited by the Examiner UNITED STATES PATENTS 3/1961 Ginaven et al. 162-18 4/1963 Ginaven et al 162-246 X 

1. A DEVICE FOR LIQUID IMPREGNATION AND TREATMENT OF CELLULOSIC MATERIAL COMPRISING AN ELONGATED CYLINDRICAL SLEEVE HAVING AN INLET AAT ONE END THEREOF AND AN OUTLET ADJACENT THE OTHER END THEREOF; SCREW FEED MEANS IN SAID SLEEVE FOR ADVANCING THE MATERIAL FROM THE INLET TO THE OUTLET; A FLUID SUPPLY CONDUIT ON THE EXTERIOR OF THE SLEEVE EXTENDING LENGTHWISE OF THE SLEEVE THE SLEEVE HAVING A BAND OF APERTURES IN ITS WALL LEADING INTO SAID CONDUIT; A FLUID DISCHARGE CONDUIT ON THE EXTERIOR OF THE SLEEVE DIAMETRICALLY OPPOSITE TO THE SUPPLY CONDUIT AND EXTENDING LENGTHWISE OF THE SLEEVE; THE SLEEVE HAVING A BAND OF APERTURES IN ITS WALL LEADING INTO SAID DISCHARGE CONDUIT WHEREBY FLUID FORCED INTO SAID SLEEVE FROM THE SUPPLY CONDUIT MAY FLOW ACROSS THE SLEEVE TO THE DISCHARGE CONDUIT. 